title: MammoSite accelerated partial breast irradiation: a single-institution outcomes analysis with 2 years of followup.
abstract: OBJECTIVE
  To provide longitudinal follow-up and assess the intermediate outcomes in breast cancer patients treated with the MammoSite radiation therapy system.
  
  
  METHODS
  Ninety-two patients with histologically proven stage 0-II breast cancer were treated with MammoSite accelerated partial breast irradiation after breast-conserving surgery. The catheter was placed at the time of surgery or postoperatively. Treatment prescription was 3.4Gy b.i.d. for a period of five days using high-dose-rate afterloading. Clinical and dosimetric parameters including dose to 90% of PTV, volume of PTV receiving 100% of dose, volume of PTV receiving 150% of dose, edited PTV, and dose homogeneity index were analyzed as variables correlating with late effects.
  
  
  RESULTS
  All patients received the prescribed treatment. Seventy-seven percent of patients had intraoperative catheter placement, which was associated with a higher rate of persistent seroma (79%). The presence of seroma did not affect cosmesis. Ten patients developed telangiectasia at a median of 20.5 months. Skin dose and balloon-to-skin distance had a significant correlation with the development of telangiectasia that significantly affected cosmetic grading. The telangiectasia incidence for maximum skin dose of >100% and >125% of the prescription dose were 28% and 63%, compared with 0% (p=0.0001) and 4.2% (p=0.0001) for doses of < or =100% and < or =125%, respectively. Overall, most patients had excellent cosmetic results, and local control of disease was excellent.
  
  
  CONCLUSIONS
  MammoSite radiation therapy system demonstrates excellent local control and cosmetic outcome with extended followup. The maximum skin dose should be kept below 100% to reduce late effects on skin and improve cosmetic outcome. The persistence of seroma is higher with intraoperative placement of the catheter, and therefore postoperative placement is preferred.
authors.affiliation: Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA, USA.
authors.forename: Marsha
authors.initials: M
authors.lastname: Haley
authors.forename: Sushil
authors.initials: S
authors.lastname: Beriwal
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Heron
authors.forename: Hayeon
authors.initials: H
authors.lastname: Kim
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Falk
authors.forename: Ronald
authors.initials: R
authors.lastname: Johnson
authors.forename: Robert
authors.initials: R
authors.lastname: Mogus
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D018714:Radiotherapy, Adjuvant / Q000379:methods; D049291:Seroma / Q000209:etiology